In this revised application entitled Function and Regulation of IL-33 in Airway Epithelial Cells in Asthma for the Mentored Clinical Scientist Research Career Development Award, I propose a comprehensive plan of research and career development at the University of California, San Francisco in the Division of Pulmonary Medicine. This proposal will not only enable me to develop the skills, techniques and collaborations necessary to establish an independent academic research career, but it will also advance the field of asthma biology. I am an ideal candidate for this mentored career development award, as I am strongly committed to establishing an independent research career. I became interested in research science as an undergraduate at the University of California, Berkeley where I worked in a virology laboratory for three years. I graduated with honors earning a full tuition scholarship to study medicine at the University of Southern California. Graduating first in my medical school class, I chose to complete my Internal Medicine residency training at UC San Diego where I performed basic science research in the laboratory of Dr. Patricia Finn. There I developed a strong interest in asthma biology and enrolled in the American Board of Internal Medicine Research Training Program. This allowed me to begin fellowship in Pulmonary Critical Care at UCSF early and spend additional years performing research. While at UCSF, I continued studying asthma in the laboratory of John Fahy. Under the research and career guidance of Dr. Fahy, Erle, Woodruff, and Sheppard, I completed a project focused on the role of periostin in asthma. I published these results in January of 2012. I have since focused on the role of IL- 33 in human asthma, and this is the topic of my current proposal. My dedication to a research career along with persistence and a track record of success will enable me to maximally benefit from this award. I have outlined a research plan in this application, which focuses on understanding the function and regulation of IL-33 in human asthma. Asthma is a chronic lung disease, which affects nearly 30 million Americans and an estimated 300 million people worldwide. Although effective treatments exist, many asthmatics do not respond optimally to available regimens; thus, novel treatments are needed. Long considered a disease of the immune system, there is increasing recognition of the importance of the airway epithelium in orchestrating the immune responses in asthma. The newly described epithelial cell cytokine IL-33 and its receptor ST2 have been strongly implicated in asthma pathogenesis in multiple large-scale genome wide association studies. Mouse models suggest that IL-33, acting through the ST2 receptor, promotes Th2 inflammation. Studies of IL-33 in human asthma are limited however. In this grant, I will focus on three important questions in IL-33 biology: 1) how is IL-33 released from airway epithelial cells, 2) what is the relationship of I-33 to Th2 inflammation in human asthma, and 3) what is the function of SNPs in the ST2 locus on the regulation of IL-33 by the soluble inhibitor sST2? IL-33 is constitutively expressed in the nuclei of airway epithelial cells, but it lacks a signal sequence, and the mechanism of its release is unknown. I have developed a novel model system by expressing GFP-tagged IL-33 in an airway epithelial cell line, which will enable me to dissect the pathways leading to IL-33 release. Once released, IL-33 is postulated to induce Th2 inflammation in the airway. Using the vast human biospecimen bank at the UCSF Airway Clinical Research Center, I will determine the relationship of IL-33 to markers of Th2 inflammation and mucous remodeling in both acute and chronic asthma. Finally, extracellular IL-33 can be regulated by its soluble inhibitor sST2. I will sequence the ST2 locus from a large number of asthmatics and identify SNPs associated with altered ST2 epithelial cell and sputum pellet gene expression. I will test the function of candidat SNPs in human primary epithelial cell culture using promoter reporter assays and a functional bioassay. This research plan will not only advance the field of asthma biology, but will enable me to develop new research skills as well as collaborations that will be essential for my success as an independent investigator. Finally, I have outlined a career development plan that takes advantage of the many opportunities here at UCSF. My primary mentor, John Fahy, is ideally suited to serve as my advisor. He brings expertise in airway epithelial cell biology and molecular phenotyping in asthma and is the director of the large UCSF human asthma tissue bank. I have assembled a team of additional advisors and collaborators, including Dr. Sheppard, Erle, Woodruff and Seibold, who have complementary skills. They will be ideal in advising me on cell biology, primary airway epithelial cell transfection, molecular cloning, biostatistics, and advanced human genetics. I will supplement the guidance of this team with formal coursework offered at UCSF in Genetics, Cell Biology, Immunology, and Biostatistics as well as weekly seminars in Immunology and general pulmonary medicine. The Department of Medicine and the Division of Pulmonary Critical Care has a strong track record of support and training for early-stage physician scientists and boasts well-resourced laboratories and core facilities. These resources will be invaluable in carrying out my research plan and will ensure my success. The Department of Medicine strongly supports my career path and this application. In July 2012, I was appointed to Assistant Professor within the Division of Pulmonary Critical Care with 80% protected research time. With these resources and support, I will be well positioned to establish a successful independent research career.